CLIMATEWIRE | Millions of acres of coastal land will be in flood zones by midcentury, potentially costing communities huge sums in lost property taxes as developed land becomes uninhabitable, an analysis released Thursday shows.

Research nonprofit Climate Central conducted a unique study of sea-level rise, projecting the amount of real estate, buildings and tax revenue that hundreds of coastal counties will lose as tides encroach on developed areas. It found that an estimated 4.3 million acres — an area nearly the size of Connecticut — will be underwater by 2050, including $35 billion worth of real estate.

“Higher flood waters are reaching further inland, flooding properties and buildings that have never flooded before,” Climate Central researchers wrote.

Louisiana could be particularly hard hit, according to the report, with 2.4 million acres underwater by 2050. On the Louisiana coast, Terrebonne Parish could see 77 percent of its acreage flood, potentially submerging 5,700 buildings.

Florida, North Carolina and Texas could also face substantial losses. In Dare County on North Carolina’s Outer Banks, for example, 27 percent of the acreage will be at risk of flooding by 2050, potentially submerging $875 million worth of real estate and buildings. Monroe County in the Florida Keys could see 19 percent of its acreage flood, representing $700 million in real estate and buildings.

“There are about 30 counties that are going to lose more than 10 percent of their land area by 2050,” Climate Central senior adviser Don Bain said.

The losses will magnify by 2100. Climate Central researchers focused on 2050 because global warming patterns are unlikely to change significantly in the next few decades. Such patterns, however, could change by the end of the century, depending on the decrease (or increase) in global emissions.

The analysis, which looked at 328 counties in 25 coastal states including Alaska and Hawaii, aims to alert state and local officials about the threat that climate change poses to tax revenue that pays for public schools, emergency protection and municipal services. It says that smaller tax bases can lead to lower tax revenues, reduced public services, and “a potential downward spiral of disinvestment and population decline.”

“If a town has no other income source but property taxes and those property taxes can’t be saved, that town is not sustainable,” said A.R. Siders, a climate resilience expert at the University of Delaware.

Mark Rupp, adaptation program director at the Georgetown Climate Center, said local property tax bases are “being washed away” by rising tides, which will force local officials to take steps such as relocating residents away from coasts and elevating roadways above flood levels.

The Climate Central report, he said, is “a really fantastic piece of work for governments” trying to plan for climate change and sea-level rise.

The report urges common adaptation strategies, such as steering development away from coastal areas.

“Frankly, we’re fiddling around on the margins, but we’re not addressing the core of the issue and we’re not thinking about it on the scale that it needs to be done,” Siders said.

By 2100, nearly 9 million acres — an area nearly the size of New Hampshire — will be underwater, including 3.2 million acres in Louisiana, or about 3 percent of its land area, according to the report. The 9 million acres includes 300,000 buildings and $109 billion worth of real estate. Overall, states in New England and on the Pacific Coast face the least potential land loss.

Climate Central researchers combined the latest sea-level rise models released last year by the Intergovernmental Panel on Climate Change with NOAA data showing coastal tide levels. They combined their analysis with property tax records to determine which parcels face a future flood threat and the value of the threatened real estate.

Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2022. E&E News provides essential news for energy and environment professionals.